More than 700 “ghost mansions” — worth a total of £3 billion — lie empty and unused in London, an Evening Standard investigation reveals today.

Research commissioned by this newspaper reveals the remarkable scale of the “no lights on” phenomenon as London faces the worst housing crisis in its history, with 800,000 people on waiting lists.

Paul Palmer, London’s leading empty homes “detective”, who previously worked for Westminster council, said his analysis showed that there were “at least” 740 uninhabited properties worth £5 million or more. He said: “The scandal of London’s posh empties continues unabated. Offshore investors are still using some of London’s finest homes as real-life Monopoly pieces, hiding behind solicitors and anonymous PO box accounts in places like the British Virgin Islands.”

He estimated the combined value of the properties at £3.2 billion, enough to fund the construction of more than 10,000 affordable homes.

The Standard’s findings shocked Mayor Boris Johnson, who said it made “little sense” for so much living space to be left unused and called on councils to levy punitive levels of council tax on owners of long unoccupied homes.

Mr Johnson said: “I would welcome boroughs following the lead of Camden council, who charge 150 per cent council tax to owners of property that has been empty for over two years. Perhaps even multiples of that could be levied to encourage owners to rent out or live in long-standing unoccupied homes.” Other prominent figures added their voices to demands for a tax on owners of empty homes, including interior designer Kelly Hoppen and architect Lord Rogers, who said “owners of buildings have a social responsibility as well as an economic one”.

The properties are scattered in a “mansion belt” stretching diagonally across London, from Wimbledon and Richmond in the south-west, to Hampstead and Highgate in the north-east. However, the great clusters are in the most elite enclaves of Mayfair, Belgravia, Knightsbridge and Kensington.

The most notorious “ghost mansion” address is The Bishops Avenue, known as north London’s “billionaire’s row”. Fifteen houses on the street, worth a total of £350 million, have been left to rot, in some cases for decades. They are in such bad repair that wildlife experts claim they are an important natural habitat for rare bats and owls and should not be demolished.

In theory, local authorities can use compulsory purchase powers to buy homes that have been unused for years. In practice, this is unlikely because of the prohibitive cost of repairing and converting them into useable homes.

It is also often hard to identify the ultimate ownership of the homes because they are hidden behind layers of complex offshore company structures.

David Ireland, chief executive of the Empty Homes charity, said London was bucking the national trend of a fall in the number of unused properties, despite having the most acute shortage.

Across the capital, there are 72,457 empty homes, of which 24,226 are classified as long-term empty, according to latest Government figures. On the streets of Mayfair this morning, there was ample evidence of fabulously expensive homes being left to rot.

On Upper Grosvenor Street — opposite the embassies of the US and Monaco — steps lead down to abandoned basement flats slowly drowning in a sea of rubbish at two run-down properties.

One passerby, writer Melissa Brady-Dant, 40, who lives in Shoreditch, said it was a “disgrace” that so many prime properties were being left empty.

“They should limit the number of foreign buyers,” she said. “There are so many people who could benefit from living in this neighbourhood. Some of the best schools are round the corner. There are lots of people who commute just to bring their children to those schools. It’s a waste, a travesty and terrible management.”

But some property experts said relaxations of planning laws and the huge demand for luxury homes in London meant more unused buildings were likely to be converted into family homes over the next few years.

Mayfair estate agent Peter Wetherell said: ”With a lot of these empty properties, there’s a lot of a activity going on below the water. There is a huge demand for really big, nice unmodernised homes — not to be left empty, but to be lived in.”